One size fits all? Stature estimation from footprints and the effect of substrate and speed on footprint creation.

Estimation of stature from footprint lengths is a common prediction in forensic cases and in palaeoanthropology upon the discovery of fossil footprints. Many studies which have estimated stature from footprints generally use a 'one size fits all' approach that usually involves applying a known ratio of foot length to total stature to do so, although this method has fallen out of practise in forensic cases in recent years but is still commonly used for fossil trace evidence. Yet, we know that substrate and speed can change the dimensions of a footprint, so why are these 'one size fits all' approaches still used today? We tested footprint production across different substrates at a walk, a fast walk and a jog. We calculated how accurately footprint dimensions were impressed between these different conditions and identified sources of error in footprint lengths, and the percentage changes of how significantly a footprint can change in length between different conditions. We provide a table with different ratios that we encourage practitioners/field scientists to refer to and use when estimating stature from footprints, with respect to the substrate on which the footprint was created and the speed at which it was created. We actively encourage researchers to add to this table by testing more substrates so that in the future stature can be more accurately estimated, thus aiding the palaeoanthropological community, but also forensic investigations by statistically highlighting how different conditions can affect trace dimensions.